Reservoirs of hydrocarbons, such as oil and gas, are typically contained within pores of an earth formation. One technique to extract hydrocarbons in the pores includes injecting water into the pores to force the hydrocarbons out of the pores and into a borehole from which they may be pumped out to the surface of the earth.
In order to monitor the extent of extraction of hydrocarbons from a reservoir to make efficient use of resources, it is useful to track the water-to-hydrocarbon interface. This may be accomplished by knowing the porosity of the formation, however, the porosity is not always known. Hence, it would be appreciated in the oil and gas industries if methods could be developed to track the water-to-hydrocarbon interface without requiring knowledge of the formation porosity.